#include <iostream>

using namespace std;

int main()
{
	int n = 0;
	cin >> n;
	int i = 0;
	string s;
	while (n)
	{
		int k = n % 2;
		if (k)
		{
			s += ('a' + i);
		}
		i++;
		n /= 2;  
	}
	cout << s;
	return 0;
}